From f86d6b7cbd6f81d451b336756f01a00dd98cbb16 Mon Sep 17 00:00:00 2001
From: Yuxuan Shui <yshuiv7@gmail.com>
Date: Thu, 25 Jul 2019 20:44:35 +0100
Subject: [PATCH] backend: update present interface for partial updates

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
---
 src/backend/backend.c         |  2 +-
 src/backend/backend.h         | 10 +++++-----
 src/backend/gl/glx.c          |  2 +-
 src/backend/xrender/xrender.c |  2 +-
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/backend/backend.c b/src/backend/backend.c
index af98791..9a9f7c6 100644
--- a/src/backend/backend.c
+++ b/src/backend/backend.c
@@ -285,7 +285,7 @@ void paint_all_new(session_t *ps, struct managed_win *t, bool ignore_damage) {
 	if (ps->backend_data->ops->present) {
 		// Present the rendered scene
 		// Vsync is done here
-		ps->backend_data->ops->present(ps->backend_data);
+		ps->backend_data->ops->present(ps->backend_data, NULL);
 	}
 
 #ifdef DEBUG_REPAINT
diff --git a/src/backend/backend.h b/src/backend/backend.h
index 4e4a8e6..a5c70d4 100644
--- a/src/backend/backend.h
+++ b/src/backend/backend.h
@@ -114,8 +114,7 @@ struct backend_operations {
 	void (*prepare)(backend_t *backend_data, const region_t *reg_damage);
 
 	/**
-	 * Paint the content of an image onto the (possibly buffered)
-	 * target picture.
+	 * Paint the content of an image onto the back buffer
 	 *
 	 * @param backend_data the backend data
 	 * @param image_data   the image to paint
@@ -134,10 +133,11 @@ struct backend_operations {
 	             const region_t *reg_blur, const region_t *reg_visible)
 	    attr_nonnull(1, 3, 4, 5);
 
-	/// Present the back buffer onto the screen.
+	/// Present part of the back buffer onto the screen.
 	///
-	/// Optional if the screen is not buffered
-	void (*present)(backend_t *backend_data) attr_nonnull(1);
+	/// @param region part of the screen that should be updated. if NULL, update the
+	///               whole screen
+	void (*present)(backend_t *backend_data, const region_t *region) attr_nonnull(1);
 
 	/**
 	 * Bind a X pixmap to the backend's internal image data structure.
diff --git a/src/backend/gl/glx.c b/src/backend/gl/glx.c
index 0013d80..2e8ccc5 100644
--- a/src/backend/gl/glx.c
+++ b/src/backend/gl/glx.c
@@ -436,7 +436,7 @@ err:
 	return NULL;
 }
 
-static void glx_present(backend_t *base) {
+static void glx_present(backend_t *base, const region_t *region attr_unused) {
 	struct _glx_data *gd = (void *)base;
 	gl_present(base);
 	glXSwapBuffers(gd->display, gd->target_win);
diff --git a/src/backend/xrender/xrender.c b/src/backend/xrender/xrender.c
index 2a07480..0b9f82a 100644
--- a/src/backend/xrender/xrender.c
+++ b/src/backend/xrender/xrender.c
@@ -301,7 +301,7 @@ static void deinit(backend_t *backend_data) {
 	free(xd);
 }
 
-static void present(backend_t *base) {
+static void present(backend_t *base, const region_t *region attr_unused) {
 	struct _xrender_data *xd = (void *)base;
 
 	if (xd->vsync) {